U.S. patent application number 14/238812 was filed with the patent office on 2014-07-24 for sensor and method for operating the sensor.
This patent application is currently assigned to GIESECKE & DEVRIENT GMBH. The applicant listed for this patent is Michael Bloss, Jorg Frankenberger, Erich Kerst. Invention is credited to Michael Bloss, Jorg Frankenberger, Erich Kerst.
Application Number | 20140204366 14/238812 |
Document ID | / |
Family ID | 46754379 |
Filed Date | 2014-07-24 |
United States Patent
Application |
20140204366 |
Kind Code |
A1 |
Frankenberger; Jorg ; et
al. |
July 24, 2014 |
Sensor and Method for Operating the Sensor
Abstract
A sensor for checking value documents is arranged to carry out a
self-test for testing its functionality. The sensor in the
self-test reacts to at least one malfunction that is ascertained
during the self-test and hinders the check of the value documents
by the sensor automatically employing for checking the value
documents, instead of the operating mode provided for checking the
value documents. A modified operating mode employs at least one
other measured value of the sensor for checking the value documents
than is determined in the operating mode provided for checking the
value documents. In contrast to the hitherto customary function
failure of the sensor, the sensor can continue being operated for
checking the value documents despite the malfunction.
Inventors: |
Frankenberger; Jorg; (Markt
Schwaben, DE) ; Bloss; Michael; (Munich, DE) ;
Kerst; Erich; (Unterfohring, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Frankenberger; Jorg
Bloss; Michael
Kerst; Erich |
Markt Schwaben
Munich
Unterfohring |
|
DE
DE
DE |
|
|
Assignee: |
GIESECKE & DEVRIENT
GMBH
Munich
DE
|
Family ID: |
46754379 |
Appl. No.: |
14/238812 |
Filed: |
August 13, 2012 |
PCT Filed: |
August 13, 2012 |
PCT NO: |
PCT/EP2012/003455 |
371 Date: |
February 13, 2014 |
Current U.S.
Class: |
356/71 |
Current CPC
Class: |
G07D 7/128 20130101;
G07D 7/121 20130101; G07D 11/26 20190101; G07D 7/2075 20130101;
G07D 11/235 20190101; G07D 7/1205 20170501 |
Class at
Publication: |
356/71 |
International
Class: |
G07D 7/12 20060101
G07D007/12 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 17, 2011 |
DE |
102011110895.9 |
Claims
1-14. (canceled)
15. A method for operating a sensor configured for checking value
documents in which at least one operating mode is provided for
checking the value documents, wherein the sensor, for testing its
functionality, carries out a self-test in which it is provided that
the sensor reacts to at least one malfunction ascertained during
the self-test and would hinder the check of the value documents in
the provided operating mode by the sensor employing for checking
the value documents, instead of the provided operating mode, a
modified operating mode in which at least one other measured value
of the sensor is employed for checking the value documents than is
determined in the operating mode provided for checking the value
documents.
16. The method according to claim 15, wherein the other measured
value is derived from measured values of the sensor that are
determined in the provided operating mode for checking the value
documents and that are not affected by the ascertained
malfunction.
17. The method according to claim 15, wherein the other measured
value is a measured value of the sensor which is not determined in
the provided operating mode for checking the value documents.
18. The method according to claim 15, wherein the sensor is an
optical sensor having several light sources which is able to detect
the light emanating from the value documents at several
wavelengths, and that the optical sensor employs for checking the
value documents in the modified operating mode, in the case of a
malfunction affecting one of the light sources, at least one other
light source than is determined in the provided operating mode.
19. The method according to claim 15, wherein the sensor is an
optical sensor which can detect the light emanating from the value
documents at several wavelengths, and that the optical sensor
employs for checking the value documents in the modified operating
mode at least one measured value that is detected at another
wavelength than the measured values that are determined in the
provided operating mode for checking the value documents.
20. The method according to claim 15, wherein the sensor is an
optical sensor which can detect the light emanating from the value
documents at several wavelengths, and that the optical sensor
employs for checking the value documents in the modified operating
mode, instead of a measured value affected by the malfunction, a
derived measured value which is derived from measured values that
are detected spectrally adjacent to the measured value affected by
the malfunction.
21. The method according to claim 15, wherein the sensor is an
optical sensor, and the self-test comprises a testing of the
function of at least one light source of the sensor and/or of at
least one photodetector of the sensor while there is no value
document present in the capture region of the sensor, wherein, for
testing the function of the light source and/or of the
photodetector, a portion of the light of the light source that is
reflected on a window of the sensor is detected by the
photodetector.
22. The method according to claim 21, wherein the self-test of the
sensor by which the function of the light source and/or of the
photodetector is tested is carried out in the gap between two value
documents transported successively past the sensor.
23. The method according to claim 15, wherein the sensor has
several measuring tracks transverse to a transport direction of the
value documents along which the value documents are transported
past the sensor for their check, and that the sensor employs for
checking the value documents in the modified operating mode, in the
case of a malfunction of one of the measuring tracks, instead of
the measured value of a measuring track affected by the
malfunction, a derived measured value which is derived from the
measured values from measuring tracks that are adjacent to the
measuring track affected by the malfunction.
24. The method according to claim 15, wherein the sensor has
several measuring tracks transverse to a transport direction of the
value documents along which the value documents are transported
past the sensor for their check, and that the sensor employs for
checking the value documents in the modified operating mode, in the
case of a malfunction of one of the measuring tracks, instead of
the measured value of a measuring track affected by the
malfunction, the measured value of another measuring track that is
adjacent to the measuring track affected by the malfunction.
25. The method according to claim 15, wherein the sensor is
configured for checking different features of value documents, and
that, before the sensor carries out the self-test, at least one of
the features that is to be checked by the sensor is selected, and
that it is provided in the self-test of the sensor that the sensor
rates a malfunction ascertained in the self-test differently in
dependence on the selected feature and reacts to the ascertained
malfunction differently in dependence on the selected feature.
26. The method according to claim 25, wherein the sensor is an
optical sensor, and the sensor rates the ascertained malfunction
differently and reacts differently to the ascertained malfunction
in dependence on the spectral properties of the selected
feature.
27. The method according to claim 25, wherein the sensor has
several measuring tracks transverse to a transport direction of the
value documents along which the value documents are transported
past the sensor for their check, and that the sensor rates the
ascertained malfunction differently, in dependence on the position
of the selected feature on the value document, and reacts to the
ascertained malfunction differently, in dependence on the position
of the selected feature on the value document.
28. A sensor for checking value documents in which there is
provided at least one operating mode for checking the value
documents, the sensor being configured for carrying out at least
one self-test for testing its functionality, in particular a
self-test according to claim 15, wherein the sensor, for testing
its functionality, carries out a self-test in which it is provided
that the sensor reacts to at least one malfunction that is
ascertained during the self-test and would hinder the check of the
value documents by the sensor employing for checking the value
documents, instead of the provided operating mode, a modified
operating mode in which the sensor employs for checking the value
documents at least one other measured value than is determined in
the operating mode provided for checking the value documents.
Description
[0001] This invention relates to a method for operating a sensor
which is configured for checking value documents, and to a sensor
which is configured for carrying out this method.
[0002] For checking value documents there are usually employed
sensors with which the kind of value document is determined and/or
with which the value documents are checked for authenticity and/or
for their state. Such sensors are employed e.g. for checking bank
notes, checks, identity cards, credit cards, check cards, tickets,
vouchers and the like. The value documents are usually checked in
an apparatus for value-document processing which contains one or
several sensors depending on the value-document properties to be
checked. For the check of the value documents, the latter are
transported past the sensor along a transport path individually
using a transport system.
[0003] For testing the function of a sensor which is arranged along
the transport path of the value documents, a test medium is usually
brought into the capture region of the sensor in order to detect a
measured value of the test medium with the sensor. For this
purpose, the value-document check is interrupted and--instead of a
value document--the test medium is brought into the capture region
of the sensor. This method is disadvantageous in that a test medium
must be provided and its association with the sensor must be
ensured. In the case of several sensors or upon replacement of the
test medium, e.g. due to degradation of the test medium, confusion
can easily arise, which can lead to false test results. Further, it
has been proposed to install a test medium in the sensor itself,
e.g. in the housing of the sensor. For testing the sensor function,
the check of the value documents is interrupted and the test medium
is swiveled into the capture region of the sensor in order to
detect measured values thereof It is disadvantageous here, too,
that the check of the value documents must be interrupted for
testing the sensor function.
[0004] Upon the functional check of a sensor it has hitherto been
tested whether measured values that the sensor detects from the
test medium brought into its capture region exceed predetermined
minimum values. As long as the actual measured values are above the
minimum value, the sensor is functional. If an undershooting of a
minimum value is ascertained, however, this results in a function
failure of the sensor. Such function failures lead to interruptions
of the operation of the sensor and the appurtenant apparatus
checking the value documents, thereby reducing the throughput of
the value-document check. Function failures usually require an
intensive testing of the sensor and/or involve manual
interventions, e.g. by service staff, and thus increase the effort
for operating the sensor.
[0005] An object of the present invention is hence to reduce the
effort for operating a sensor configured for checking value
documents.
[0006] This object is achieved by the subject matter of the
independent claims. Claims dependent thereon state advantageous
developments and configurations of the invention.
[0007] The method according to the invention relates to a sensor
which is configured for checking value documents. The sensor can be
a sensor for checking optical or magnetic or electrical or
mechanical properties of the value documents, in order to check the
value documents for their authenticity, their kind, their state or
their quality. For checking the value documents there is provided
in the sensor at least one operating mode of the sensor in which it
is determined which measured values the sensor is to detect for
checking the value documents and how the detected measured values
are to be evaluated. The sensor has e.g. a data memory in which
there is stored the provided operating mode or information on the
provided operating mode employed by the sensor for checking the
value documents. The sensor can have provided therein one or also
several operating modes, e.g. for checking one or several kinds of
value document.
[0008] For ascertaining any malfunctions, the sensor carries out a
self-test by which it tests its functionality autonomously. The
sensor can be configured for carrying out one or several
self-tests. If no malfunction is ascertained in the self-test of
the sensor that has been carried out, the sensor employs for
checking the value documents the operating mode that is provided
for checking the value documents, and carries out a check of the
value documents in the provided operating mode.
[0009] In the self-test it is provided that the sensor reacts to at
least one malfunction that is ascertained during the self-test and
would hinder the check of the value documents by the sensor
employing a modified operating mode for checking the value
documents, instead of the operating mode provided for checking the
value documents. In the modified operating mode there is employed
for checking the value documents at least one other measured value
of the sensor than is determined in the operating mode provided for
checking the value documents. In contrast to the hitherto customary
function failure of the sensor, the sensor can hence continue being
operated for checking the value documents despite the malfunction.
Although the malfunction would hinder the check of the value
documents, the sensor only fails when there is no possibility for
the sensor to circumvent the malfunction using the modified
operating mode. In many cases the sensor will be able to circumvent
the malfunction, so that--instead of failing--it can continue being
operated and can carry out a check of the value documents despite
the malfunction. By employing a modified operating mode in which
another measured value is employed, it is achieved that the number
of function failures of the sensor is reduced. Employing another
measured value moreover has the advantage that the evaluation of
the measured values must only be slightly changed, because the
provided measured value merely needs to be replaced by the other
measured value, while the evaluation can otherwise remain the
same.
[0010] The other measured value is e.g. a measured value that is
derived from measured values of the sensor that are employed in the
provided operating mode but are not affected by the malfunction.
For example, the other measured value can be a measured value
interpolated or extrapolated from the detected measured values. The
other measured value can also be a measured value of the sensor
that is not at all determined for checking the value documents in
the provided operating mode. The other measured value can e.g. be
an additionally detected measured value that is not detected in the
provided operating mode but is detected and evaluated in the
modified operating mode, or it can be an additionally evaluated
measured value that is detected but not evaluated in the provided
operating mode. Employing an additional measured value has the
advantage that measuring information lost through the malfunction
can be at least partly compensated by the additional measured
value.
[0011] In the modified operating mode, a measured value that is
affected by the malfunction and was to be employed in the provided
operating mode can be omitted. For example, the affected measured
value is also detected in the modified operating mode but is not
taken into consideration in the evaluation of the measured values,
and the evaluation is carried out on the basis of the remaining
measured values which are not affected by the malfunction. Or the
measured value affected by the malfunction is not at all detected
in the modified operating mode. In the case of an optical sensor,
the relevant light source in an illumination sequence can e.g. be
omitted, or the relevant measured value not detected or not taken
into consideration in the evaluation. In a sensor having several
measuring tracks transverse to a transport direction of the value
documents, the measured value of the relevant measuring track can
be omitted, e.g. ignored upon the evaluation.
[0012] While in the provided operating mode the value documents
would be checked on the basis of one or several measured values
that are affected by the malfunction, in the modified operating
mode the value documents are preferably checked exclusively on the
basis of measured values of the sensor whose generation is not
affected by the malfunction. The check of the value documents is
carried out e.g. on the basis of those measured values already
provided hitherto that are not affected by the malfunction, and on
the basis of one or several additional measured values that are not
affected by the malfunction. The modified operating mode differs
e.g. by an excitation that is modified in comparison to the
provided operating mode, e.g. by employing another light source in
the case of an optical sensor.
[0013] In the self-test it can be provided that the sensor reacts
to one or several malfunctions in this way. In the case of
different such malfunctions the sensor can react in the same or in
a different way. Furthermore, there can also be further
malfunctions of the sensor that result in a function failure of the
sensor, e.g. when the sensor has no modified operating mode
available for this malfunction in order to circumvent the
malfunction.
[0014] Upon ascertainment of a malfunction the sensor can store
information about the ascertained malfunction in an error memory,
in order for the information on the ascertained malfunction to be
available later. If the sensor ascertains a malfunction and the
ascertained malfunction would not hinder the check of the value
documents, the sensor carries out the check of the value documents
in the provided operating mode. In this case no circumvention of
the malfunction is necessary and the ascertained malfunction can be
ignored in the check of the value documents.
[0015] If the sensor ascertains during its self-test a malfunction
that would hinder the check of the value documents and the
malfunction is circumventable, the sensor reacts by replacing the
provided operating mode by the modified operating mode or suitably
modifying the provided operating mode for checking the value
documents, and carrying out the check of the value documents in the
modified operating mode. Moreover, it can be provided that the
sensor reacts to the same malfunction in certain other cases when
the malfunction is not circumventable by the sensor outputting an
error message indicating a non-functionality of the sensor or of a
certain function of the sensor. The sensor can display the error
message itself and/or send it via the communication interface to
the apparatus in order to display the error message and/or process
it further.
[0016] The self-test is carried out in particular by a sensor
already installed in an apparatus for checking value documents. The
sensor carries out the self-test e.g. in the interim between the
check of value documents to be successively checked. Additionally
or alternatively, the sensor can also carry out the self-test
before the onset of the value-document check, e.g. when the sensor
or the apparatus is started up. The information on how the sensor
can react to the respectively ascertained malfunction is stored
e.g. in the data memory of the sensor. It is advantageous here that
the sensor can perform its self-test fully autonomously and the
sensor e.g. requires no data exchange with its environment for this
purpose. Alternatively, the information on the different reactions
can also be fed to the sensor from outside, however, e.g. through
the above-mentioned apparatus.
[0017] When the sensor is an optical sensor, the self-test
comprises e.g. a test of the function of at least one light source
of the sensor and/or of at least one photodetector of the sensor.
For testing the function of the light source and/or of the
photodetector, a portion of the light of the light source that is
reflected on a window of the sensor is detected by the
photodetector while no value document is present in the capture
region of the sensor. Because this self-test requires no test
medium and no value document, the self-test of the sensor is
already possible before the onset of the value-document check.
Moreover, this self-test can also test measuring tracks of the
sensor that lie outside the value document to be checked. The
hitherto customary employment of a test medium does not enable such
edge measuring tracks to be tested, in contrast. For testing the
function of the light sources, the portion of the light of the
light source that is reflected on a window of the sensor is
detected by that photodetector that also detects the light
emanating from the value document for checking the value documents.
Hence, no additional detector needs to be provided for the purpose
of checking the light sources during the self-test. The self-test
of the sensor by which the function of the light sources and/or of
the photodetectors is tested can be carried out in the gap between
two value documents transported successively past the sensor. In
particular, the self-test can be carried out in each of these gaps
or regularly after a certain time or number of value documents, or
the self-test can be carried out before a change to other value
documents.
[0018] When the self-test of the sensor is carried out in this way,
it comprises not only a test of the function of the light sources,
but automatically also a test of the function of the photodetector.
Using logical analyses it can be found out which of the light
sources and/or of the photodetectors are affected by the
malfunction. When e.g. the light of several light sources is
detected successively with a certain photodetector, and the
photodetector detects an insufficient signal upon the switch-on of
each of these light sources, one can infer a malfunction of the
photodetector or of the electronic circuit connected thereto. When
the photodetector only detects an insufficient signal for one of
these light sources, however, one infers a malfunction of this
light source or its power supply or drive. A malfunction can
already be ascertained on the basis of one insufficient measured
value, or only through several measured values that indicate a
malfunction. The sensor can additionally or alternatively also
carry out different kinds of self-tests and identify malfunctions
using other methods. Depending on which malfunction is ascertained
and whether or not it is circumventable, the sensor might employ
one of its modified operating modes for checking the value
documents.
[0019] When the sensor is an optical sensor that detects the light
emanating from the value documents at several wavelengths, there
can be employed for checking the value documents in the modified
operating mode at least one measured value that is detected at
another wavelength than the measured values that are provided in
the provided operating mode for checking the value documents. In
particular, the measured value detected upon illumination with
another wavelength can be employed. In the case of spectrally
different light sources, this can be obtained e.g. by a spectrally
different illumination and, where applicable, an accordingly
adapted evaluation. In the case of spectrally different
photodetectors, a measured value can be detected and evaluated at
another wavelength with identical illumination. Advantageously,
upon the check of a spectrally broad-band feature of the value
documents, the function failure of a light source or of a
photodetector can be avoided when a spectrally adjacent light
source or a spectrally adjacent photodetector is also suitable for
checking the feature.
[0020] When the sensor is an optical sensor that detects the light
emanating from the value documents at several wavelengths, there
can be employed for checking the value documents in the modified
operating mode at least one derived measured value, e.g. instead of
the measured value affected by the malfunction. The employment of a
derived measured value, e.g. interpolated or extrapolated measured
value, has the advantage that the evaluation can remain
substantially the same, because the deriving step only needs to be
added before the evaluation while the evaluation can otherwise
remain the same. The interpolated measured value is interpolated
e.g. from the detected measured values that are detected on both
sides spectrally adjacent to the measured value affected by the
malfunction. For example, in the case of a malfunction of one of
the light sources there is employed, instead of the measured value
that is detected upon illumination with the malfunctioning light
source, an interpolated measured value that is interpolated from
measured values that are detected upon illumination with light
sources that are spectrally adjacent to the malfunctioning light
source. In the case of spectrally resolved detection, the measured
values of spectrally adjacent photodetectors are accordingly
interpolated.
[0021] An optical sensor having several light sources can employ
for checking the value documents in the modified operating mode, in
the case of a malfunction of one of the light sources, one or
several other light sources than is determined in the provided
operating mode. The illumination can for this purpose be changed
over to one or several other light sources. The check of the value
documents is carried out e.g. exclusively using those light sources
that are not affected by the malfunction. Instead of the light
source affected by the malfunction there can be employed the
spectrally identical wavelength, if present in the sensor.
Otherwise there can also be employed one or several light sources
of another wavelength whose spectrum differs from the light source
provided in the provided operating mode.
[0022] If the sensor is a sensor having several measuring tracks
transverse to a transport direction of the value documents along
which the value documents are transported past the sensor for their
check, there can be employed for checking the value documents in
the modified operating mode, in the case of a malfunction of one of
the measuring tracks, a derived measured value instead of the
measured value of the malfunctioning measuring track. The derived
value can be interpolated from the measured values of the measuring
tracks adjacent to the malfunctioning measuring track.
Advantageously, the evaluation can remain substantially the same in
this case, too, because only an interpolation step before the
evaluation is necessary. The sensor can employ for checking the
value documents in the modified operating mode, in the case of a
malfunction of one of the measuring tracks, instead of the measured
value of the malfunctioning measuring track, the measured value of
another measuring track that is most closely adjacent to the
malfunctioning measuring track. This makes it possible to avoid
function failures of the sensor when checking spatially extensive
features of the value documents.
[0023] The invention also relates to a sensor which is configured
for checking value documents and which is configured, e.g.
programmed, for carrying out the self-test according to the
invention in which the sensor tests its functionality. In the
self-test of the sensor it is provided that the sensor reacts to a
malfunction that is ascertained during the self-test and would
hinder the check of the value documents by the sensor employing for
checking the value documents, instead of the provided operating
mode, a modified operating mode in which at least one other
measured value of the sensor is employed for checking the value
documents than is determined in the operating mode provided for
checking the value documents. The sensor is moreover so programmed
to subsequently carry out the check of the value documents in the
modified operating mode. In a data memory of the sensor there can
be stored one or several provided operating modes or information
thereon as well as one or several modified operating modes or
information thereon from which the sensor can take or derive how to
react to the respective malfunction. The data memory can be
integrated in the housing of the sensor, or the data memory is a
data memory present outside, e.g. data memory of the apparatus to
which the sensor is connected.
[0024] To enable a check of different features, e.g. authentication
features, of value documents or of different kinds of value
document, different operating modes can be provided in the sensor.
For this purpose, the data memory of the sensor has for example
stored therein for each of the different features a respective
provided operating mode or information on the respective provided
operating mode which the sensor employs for checking the respective
feature. Before the sensor carries out its self-test, at least one
of the features that is to be checked by the sensor can be
selected. Upon the self-test of the sensor it can be provided that
the sensor rates a malfunction ascertained in the self-test
differently in dependence on the selected feature and that the
sensor reacts to the malfunction ascertained in the self-test
differently in dependence on the selected feature. There can
furthermore also be malfunctions for which it is determined that
the sensor always reacts in the same way, independently of the
selected feature. In the case of an optical sensor, the sensor can
rate the malfunction differently and react to the malfunction
differently for example in dependence on the spectral properties of
the selected feature, in particular in dependence on the spectral
position and/or the spectral pattern of the feature. If the sensor
is a sensor having several measuring tracks transverse to a
transport direction of the value documents, the sensor can rate the
ascertained malfunction differently and react differently to the
ascertained malfunction in dependence on the position of the
respective feature on the value document. The information on the
different reactions that the sensor is to perform upon the
ascertained malfunction, in dependence on the selected feature, is
stored e.g. in the data memory of the sensor. From this information
the sensor can derive or take the different reactions.
[0025] In the self-test of the sensor it can be provided that the
sensor rates a malfunction ascertained during its self-test
differently in dependence on the selected kind of value document
and that the sensor reacts to the malfunction ascertained during
the self-test differently in dependence on the selected kind of
value document. Kinds of value document are understood to be e.g.
bank notes, checks, identity cards, credit cards, check cards,
tickets, vouchers or a certain sort or version of the same. The
kind of value document can also be a selection of several different
sorts of value documents, e.g. value documents with certain
features or value documents with certain size specifications. In
the case of bank notes, the kind of value document can be the
denomination, the currency, the emission or a statement about a
selection of different denominations and/or currencies.
[0026] Hereinafter the invention will be explained by way of
example with reference to the following figures. There are
shown:
[0027] FIG. 1a a sensor for checking value documents which carries
out a self-test,
[0028] FIG. 1b a kind of value document W equipped with two
features, and two kinds of value document W1, W2 which are
respectively equipped with one feature,
[0029] FIG. 2a spectral distribution of the light emanating from a
feature of a value document, for two features,
[0030] FIG. 2b four malfunctions and appurtenant different
reactions of the sensor, for two different features,
[0031] FIG. 3 flowchart on the run of the self-test.
[0032] FIG. 1 shows a sensor which carries out a self-test
according to the invention. As an example there was chosen an
optical sensor 100 which has measuring elements 4, including one or
several light sources 41 and one or several photodetectors 43, as
well as, where applicable, further optical elements such as e.g.
lenses, filters, etc. A value document 10 to be checked is checked
while it is being transported past the sensor 100 along a transport
direction T. For the check of the value document 10 the latter is,
when it is located in the capture region of the sensor, illuminated
by the light emitted by the light source(s) 41, and the light that
is sent off by the value document as a result of the illumination
is detected using the photodetector(s) 43. What is detected is e.g.
the luminescent light or remitted light of the value document 10.
The optical sensor 100 is configured in this example for detecting
the light sent off by the value documents at several different
wavelengths from .lamda..sub.1 to .lamda..sub.7, cf. FIG. 2a. For
this purpose, the detector has e.g. several light sources with
different emission spectra or several photodetectors with
spectrally different sensitivities, e.g. photodetectors equipped
with different filters.
[0033] FIG. 2a shows for two features M1 and M2 of value documents,
e.g. authentication features, the respective spectral intensity
distribution of the light that is sent off by a value document
having the respective feature. FIG. 1b top shows by way of example
a kind of value document W which is equipped with the two features
M1, M2. FIG. 1b middle shows another kind of value document W1
which has only the feature M1, and FIG. 1b bottom shows a further
other kind of value document W2 which is equipped only with the
feature M2. Because the two features M1, M2 are present at
different positions on the respective value document, different
measuring tracks are relevant for the check of the two features M1
and M2.
[0034] The sensor 100 has a control device 3, e.g. a processor,
which controls the measuring elements 4 for carrying out the
self-test as well as for checking the features and evaluates the
thereby detected measured values according to the respective
operating mode. The control device 3 is connected to a data memory
5 of the sensor which has stored therein information on the
different operating modes of the sensor 100 for one or several
features Mn=M1, M2. . . . These include the wavelengths and
measuring tracks provided for the check of the respective feature
Mn as well as information on the evaluation that is to be applied
for checking the respective feature.
[0035] In the data memory 5 there is contained for example the
information on the operating modes from Table 6, cf. FIG. 2b,
through which the features M1, M2 have associated therewith the
operating modes B1, B2 that the sensor is to employ upon the check
of the respective feature. The information on the operating mode
comprises here the wavelengths and measuring tracks to be evaluated
upon the check of the respective feature, and the evaluation to be
employed. In this example, measured values for the same wavelengths
.lamda..sub.1-.lamda..sub.7 and measuring tracks L1-L10 are to be
detected in both operating modes B1 and B2, but different
evaluations carried out. In the operating mode B1 for checking the
feature M1, the wavelengths .lamda..sub.1, .lamda..sub.3,
.lamda..sub.5, .lamda..sub.6 and .lamda..sub.7 are provided for
evaluation, namely in the measuring tracks L8 to L10. And in the
operating mode B2 for checking the feature M2, the wavelengths
.lamda..sub.1 to .lamda..sub.5 are provided for evaluation, namely
in the measuring tracks L3 to L10. Further, Table 6 also contains
information on the reactions R1, R2, . . . of the sensor to
ascertained malfunctions. Furthermore, the data memory 5 can
contain the information of Table 9 through which the sensor can
establish from a selected kind of value document Wn the appurtenant
features Mn. In addition, the data memory 5 can also store further
information for checking the features, e.g. reference data of the
respective feature with which the detected measured values are
compared upon the check of the feature.
[0036] The sensor 100 further has a communication interface 2 via
which it can receive and output information. To initiate the check
of a certain feature, information can be fed to the sensor 100
before the value-document check via the communication interface 2
about which of the different features Mn or which of the kinds of
value document Wn is to be checked by the sensor. For example, it
is fed to the sensor via the communication interface 2 that it is
to check the feature M1. To inform the sensor of the features to be
checked, it suffices for the kinds of value document W1 and W2 to
inform the sensor only of the kind of value document. For this
purpose, only the information is e.g. fed to the sensor about which
kind of value document Wn it is to check. For example, the sensor
is informed that the kind of value document W1 is to be checked.
Using the information 9 deposited in the data memory the sensor can
unambiguously establish from this kind of value document W1 the
feature M1 to be checked, and analogously M2 from W2.
[0037] Alternatively, the sensor can also carry out the
value-document check without a previous selection of a feature Mn
or of a kind of value document Wn, e.g. when the sensor 100 has
provided therein only one operating mode in which the sensor checks
one or several certain features Mn. For example, only the operating
mode B1 is provided, so that there is no selection of the feature
M1. Upon certain malfunctions for which a circumvention is
provided, a modified operating mode BP is then employed, cf. FIG.
2b.
[0038] At the time represented in FIG. 1 a, there is no value
document 10 located in the capture region of the sensor 100. In
this gap between the value documents 10, the function of the light
sources 41 of the sensor is e.g. tested during the self-test. For
this purpose, the light sources 41 are switched on individually one
after the other in the gap between two value documents 10, and the
light of the light sources partly reflected back on the window 8 of
the sensor is respectively detected using the photodetector 43. On
the basis of the light intensity detected from the individual light
sources the sensor 100 ascertains whether or not a malfunction of
the respective light source 41 is present. A malfunction of a light
source is ascertained e.g. when the detected light intensity of the
light source undershoots a certain minimum value. Analogously, the
function of the photodetectors 43 can also be tested. The self-test
can additionally or alternatively comprise a test of electronic
components of the sensor, e.g. by checking an electrical voltage.
The sensor can also employ the respective modified operating mode
upon a malfunction of a component on whose function the light
source or the photodetector depends.
[0039] For carrying out the self-test of the sensor 100 one can
proceed e.g. according to the flowchart represented in FIG. 3.
Before the self-test is carried out the sensor can, if this is
provided, be informed via the communication interface 2 of the
feature Mn to be checked or of the kind of value document Wn to be
checked. This can be effected before or during the value-document
check. The sensor 100 then carries out the self-test before or
during the value-document check, e.g. in the gap between two value
documents. In the checking step S10 the sensor decides on the
result of the self-test: If the sensor passes the self-test, the
check of the selected feature Mn is carried out on the relevant
value documents having the feature Mn. If the sensor ascertains a
malfunction F, however, the self-test is not passed. A non-passing
of the self-test does not automatically lead to a non-functionality
of the sensor, however. For the sensor checks whether or not the
ascertained malfunction F is relevant for checking the selected
feature Mn (checking step S20). Corresponding information 6 is
deposited in the data memory 5, cf. FIGS. 1a and 2b. If the
malfunction F does not hinder the check of the feature Mn, the
check of the selected feature is carried out as provided. However,
a corresponding entry is written to the error memory 7 of the
sensor. If the sensor ascertains in the checking step S20 that the
ascertained malfunction F hinders the check of the selected feature
Mn, the sensor distinguishes between the two cases of whether or
not the malfunction F is circumventable for the selected feature Mn
(checking step S30). For this purpose, the sensor 100 tests whether
its data memory 5 contains information for the selected feature Mn
about how to deal with the ascertained malfunction F in the case of
the feature Mn, e.g. whether for the selected feature Mn
information is contained for a modified operating mode for
circumventing the ascertained malfunction F. If no modified
operating mode is provided for the selected feature Mn for
circumventing the malfunction F, the sensor ascertains that it is
not functional for checking the feature Mn and emits a
corresponding error message e.g. via the communication interface 2
to the outside and writes a corresponding entry to the error memory
7. For example, the check of the value documents is thereupon
stopped. Upon the check of different kinds of value document, the
value documents in which this feature Mn is to be checked can also
be rejected upon the check (reject stacking), while the remaining
kinds of value document are checked as provided. However, if the
sensor 100 finds in the Table 6 information on a modified operating
mode through which the ascertained malfunction F is circumventable
for the selected feature Mn, it chooses this modified operating
mode. In this way the sensor circumvents the ascertained
malfunction F, and the check of the selected feature Mn is carried
out in the modified operating mode.
[0040] The data memory 5 of the sensor contains e.g. the
information stated in Table 6 on the reactions of the sensor to a
malfunction ascertained during the self-test, cf. FIG. 2b. On the
basis of this information the sensor decides how to react to the
ascertained malfunction for the respectively selected feature Mn.
FIG. 2b specifies four examples of malfunctions F1-F4 and
respective information on how the sensor is to rate one and the
same malfunction differently in dependence on the feature M1 or M2
and respectively react differently thereto:
Malfunction F1:
[0041] In the self-test of the sensor a malfunction F1 of the light
source .lamda..sub.3 is ascertained. If the feature M1 was
selected, the sensor ascertains on the basis of the information on
the operating mode B1 that this malfunction F1 would hinder the
functionality of the sensor. On the basis of the information of
Table 6, however, the sensor ascertains that the malfunction F1 can
be circumvented for the feature M1 by employing for checking the
feature M1--instead of the measured value detected upon
illumination with the malfunctioning light source
.lamda..sub.3--another measured value, namely the measured value
detected upon illumination with the functional light source
.lamda..sub.4, cf. FIG. 2a. In the case of the feature M2 the
sensor takes from Table 6 that the malfunction F1 is relevant for
the check of this feature M2 and not circumventable. The sensor
thereupon emits an error message that it is not functional for
checking the feature M2 or the relevant value documents due to the
malfunction F of the light source .lamda..sub.3.
Malfunction F2:
[0042] In the self-test of the sensor a malfunction F2 of the light
source .lamda..sub.5 is ascertained. If the feature M1 was
selected, the sensor ascertains on the basis of the information on
the operating mode B1 that this malfunction F2 would hinder the
functionality of the sensor. On the basis of the information of
Table 6 the sensor further ascertains that the malfunction is not
circumventable for this feature M1. The sensor thereupon emits an
error message that it is not functional for checking the feature M1
or the relevant value documents due to the malfunction F2 of the
light source .lamda..sub.5. In the case of the feature M2, however,
the malfunction F2 can be circumvented by the measured value
detected upon illumination with the malfunctioning light source
.lamda..sub.5 not being employed for checking the feature M2, as
provided in the operating mode B2, but rather the relevant measured
value being dispensable, cf. FIG. 2a.
Malfunction F3:
[0043] In the self-test of the sensor a malfunction F3 of the light
source .lamda..sub.6 is ascertained. If the feature M1 was
selected, the sensor ascertains on the basis of the information on
the operating mode B1 that this malfunction F3 would hinder the
functionality of the sensor. On the basis of the information of
Table 6, however, the sensor ascertains that the malfunction is
circumventable for this feature M1 by employing another measured
value, namely by interpolating the measured values that are
detected at .lamda..sub.5 and 4 The measured value detected upon
illumination with .lamda..sub.6 is then, for the evaluation,
replaced by the measured value .lamda..sub.6* calculated by means
of interpolation. In the case of the feature M2 the sensor takes
from the information on the operating mode B2 that the check of the
feature M2 is not hindered by the malfunction F3. The check of the
feature M2 or of the relevant value documents can be carried out
with the provided operating mode B2.
Malfunction F4:
[0044] In the self-test of the sensor a malfunction F4 of the
measuring track L5 is ascertained, e.g. a malfunction of the
photodetector of the measuring track L5. If the feature M1 was
selected, the sensor ascertains on the basis of the information on
the operating mode B1 that this malfunction F4 does not hinder the
check of the feature M1. The check of the feature M1 or of the
relevant value documents can be carried out with the provided
operating mode B1. In the case of the feature M2 the sensor takes
from Table 6 that the malfunction F4 would hinder the functionality
of the sensor, but is circumventable for this feature M2 by
employing another measured value, namely by interpolating the
measured values that are detected in measuring track L4 and in
measuring track L6. The measured value from measuring track L5 is
then, for the evaluation, replaced by the measured value L5*
calculated by means of interpolation.
[0045] During the self-test there are always tested for example,
independently of the selected feature, all light sources or
photodetectors of the sensor. However, the results of the self-test
are rated differently in dependence on the kind of value document,
cf. FIG. 2b. To accelerate the self-test, different self-tests can
also be carried out in dependence on the selected feature. By the
self-test there can be tested e.g. only those respective light
sources or photodetectors that are provided for checking the
respectively selected feature. If the feature M1 was selected, the
self-test can be limited to the light sources of the wavelengths
.lamda..sub.1, .lamda..sub.3, .lamda..sub.5, .lamda..sub.6 and
.lamda..sub.7 in the measuring tracks L8 to L10. And if the feature
M2 was selected, the self-test can be limited to the light sources
of the wavelengths .lamda..sub.1 to .lamda..sub.5 in the measuring
tracks L3 to L10.
* * * * *